


Won't You Be My Soulmate?

by SoloShikigami



Category: Undertale (Video Game)
Genre: M/M, Soul Binding, Soul Sex
Language: English
Status: Completed
Published: 2019-09-29
Updated: 2019-09-29
Packaged: 2020-10-30 06:08:55
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings, No Archive Warnings Apply
Chapters: 1
Words: 4,678
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/20809814
Author URL: https://archiveofourown.org/users/SoloShikigami/pseuds/SoloShikigami
Summary: A follow-up to the drabble, "How I Feel About You" (found here: https://archiveofourown.org/works/7514545/chapters/17187025) in which Fell follows through with his promise, especially after a battle leaves them both relatively... rattled.





	Won't You Be My Soulmate?

**Author's Note:**

  * For [4nn1e_Ch0kab0](https://archiveofourown.org/users/4nn1e_Ch0kab0/gifts).

** **

Fell didn’t keep his promise to return the favor right away, but it wasn’t his fault. One of the drawbacks of universes colliding was when their antagonists teamed up.  
  
The newest universe-set of monsters brought along a frightening amalgamation of a genocidal human, an Evil Flowey, and an Evil Temmie. Papyrus and Fell proved to be great battle leaders, Blue’s enthusiasm kept their morale up, and the younger brothers quickly learned the hidden strengths their older brothers possessed.  
  
Once the battle was over, the newly arrived Sans and Papyrus were given the nicknames Black and Pup, and they all started to settle back into their previously mundane, but welcome, peaceful lives.

That was when Swap discovered another drawback of their multiple universes colliding – it had triggered flashback nightmares for him.

Swap would wake up during the night in cold sweats, his soul aching and pounding, flashes of his brother’s head falling into the snow, the sadistic grin of the human, Temmie cackling and reminding him how useless and pathetic he was, that he was trash, a horrible monster, sitting back and watching everyone die, and not doing one thing to stop-

“SWAP!”

Swap gasped and jolted. He looked around frantically and realized he was in his room, messy as always, and Fell was gripping him hard by the shoulders and apparently had been shaking him.

“H-h-hey,” Swap said shakily. “’sup?”

Fell glared and let go of him, then he stood up and crossed his arms. Swap leaned back on his elbows.

“I think you know what’s “_sup,_” Swap,” Fell said flatly. “I have noticed that you have been quieter recently, and you have cancelled two of our dates.”

“Oh? Paying that much attention to me? You must love me,” Swap said with a grin.

Fell made a small growl and passed his hand over his face. As it passed, the angry demeanor dropped, his face relaxed into a more concerned look, and that bothered Swap more than the angry look.

“Of course I love you, Swap, I had told you that weeks ago, I let you handle my soul and make love to it, even.”

“We didn’t really have sex,” Swap began to argue.

“Not soul sex, no, but still, handling another’s soul the way you did is quite… uhm… intimate,” Fell’s voice dropped into a murmur as he looked away with a blush.

Swap chuckled, admiring how cute Fell looked when he blushed. Fell seemed to notice and shake his head as if to shake off the dusting of red on his cheekbones. It didn’t work.

“Enough of that. Anyway, my brother has informed me that he used to have nightmares, and it was suggested that you possibly are afflicted the same way. Blue has told me that you’ve been sleeping in and slacking in the responsibilities that you have been building on since you arrived here.”

“That little traitor.”

“I asked him.”

“Why not just ask me?”

“When was the last time you checked your phone messages, asshole?”

Swap blinked and looked around for his phone. He started looking through the covers and patting down the crumpled sheets when a sigh distracted him. He looked up and watched Fell walk over to the head of his bed, reach behind the mattress, and pull his phone from between it and the wall.

“How the hell did you know it was there?” Swap asked, taking the phone and grimacing at the three percent battery power that was left.

“Because the few times I have spent the night here, that was where it ended up if I didn’t take it myself to put aside,” Fell smirked a little. “Those were our, _ahem_, rougher nights.”

Swap would have normally laughed or teased back, but his eyes were busy scanning the many text messages he missed since he cancelled their last date four days ago. Fell’s were the most numerous, some messages were from his other friends and a few from his own brother, mostly telling him to get up or that meals were ready.

“I’m sorry,” Swap said, dropping the phone on the carpet and rubbing his eyes, ignoring the one last buzz the phone gave as the battery finally died.

“It’s okay, I understand,” Fell said, slowly moving to the bed and sitting next to Swap.

They silently sat there for a little while and Fell found it uncomfortably reminiscent of their morning-afters when they first started sleeping together. It was hard to imagine that there was a time that they annoyed the hell out of one another, putting up with each other for their brothers and friends. Papyrus and Blue wanted them to get along for the sake of friendship, Sans and Red wanted them to at least put up with each other because life had been hell to them both and all they wanted now was peace and quiet. Swap was in the same boat as Sans and Red and really just wanted a nice, peaceful life to the end of his days as well, but Fell was a constant thorn in his side, throwing out criticisms and insults directly to him, and then Swap started throwing them back, and their bickering began.

They soon came to enjoy the banter, a small, reluctant respect grew as they learned more about one another, the respect (and frankly, loneliness), turned into passion, and then it slowly turned into genuine love for one another.

Fell was a little worried that the love between them had faded, however he was more concerned over Swap suddenly losing the fragile stability he had before the incident, and there were a few other things on Fell’s mind that he wanted to put out in the open before something else happened.

“Swap, I still love you, very, very much,” Fell murmured after a while. “During our battle against that horrendous creature, I couldn’t help but think of the ways it all could go wrong, that if I failed, if any of us failed, that I could lose you.”

There were a few times where they had lost track of one another while everything was in chaos, sometimes not even knowing who was alive beyond the dust and who was part of that dust. It happened so many times, and each time, Swap felt sick and his soul stuttered.

“Yeah,” Swap murmured. “I… I’ve had a few nightmares about losing you, or Sans, but I don’t want to talk or think about it.”

“I’m willing to listen whenever you like,” Fell assured him, reaching over to take his hand and giving it a firm squeeze. “I don’t ever want to lose you either, Swap, and to be honest, your one hit point has me worried. If you are in trouble, I want to be able to help you.”

“Heh, yeah, sure, and how are you gonna do that, Fell? It’s a nice notion and all, but unless you are chained to me or something, I don’t see how it’s possible,” Swap said, giving Fell a meaningful but slightly sad smile.

“It is very possible, and it is something I have been thinking about since I started realizing my feelings for you, which had begun before the night I trusted you with my soul,” Fell said.

“Oh, come on, we fought like there was no tomorrow, you can’t really mean... that... what are you doing?”

Fell had slid off the bed and dropped to one knee in front of Swap.

“I mean what I say,” Fell said, reaching up to take Swap’s hands. “I did not come to this decision lightly. Papyrus, I want to soul-bond with you.”

Swap’s eyes went wide.

“Y-you want to wh-wha-what?!” he stammered.

“I want to soul-bond with you, I want our souls to be connected, I want my strength to bolster yours, I want to know that you’re safe, I want you to know that I’m safe, I want to spend the rest of my life with you.”

“Well, yeah, I mean, I want to spend the rest of my life with you, too, but like, I kinda don’t believe in that soul-bonding, mate-for-life sort of thing, you know?”

Flashes of who knew how many timelines flashed through Swap’s eyes, and the thought of losing Fell already making his soul ache.

“Swap, my love, I understand where this hesitance is coming from,” Fell said, reached up to touch Swap’s face. “And this is why I want to share our burdens, regardless of the dangers involved. If something happens, I’ll be in the same agony and pain as you. I don’t want you to go through that alone anymore. Please, don’t cry.”

Swap realized that he was shaking, Fell’s thumb brushing the stream of tears away. Swap gripped the hand caressing his face, squeezing his eyes shut in an attempt to stop the flow.

“I don’t know if I can live with putting you through that,” Swap whispered.

“And I don’t want you to suffer by yourself, I love you,” Fell said, leaning in to kiss the corner of Swap’s mouth before pressing his forehead against his. “Hey, just think about it, all right? I will still love you regardless of your decision, and I want you to take all the time you need.”

Fell gave him one more kiss on the forehead, giving his hand a small squeeze before leaving him to think.

* ~ * ~ * ~ * ~ * ~ * ~ * ~ * ~ * ~ *

“Whoa, I didn’t know the guy even had the capability to care,” Sans said.

“Oh, come on, Sans, he’s only a rougher version of Papyrus, he would have turned out like Fell if you guys grew up in their world,” Swap sighed, squirting honey into his mouth, letting it sit on his tongue for a moment before swallowing.

“Yeah, maybe,” Sans said, reluctant to admit that one the skeletons he got along with the least was anything close to resembling his own precious brother. “What are you gonna do?”

“That’s why I’m talking to you,” Swap said. “I don’t know what to do.”

“I guess the obvious question is, do you love him, too?”

“I do, I mean, how could I not? The guy trusted me with his soul for fuck’s sake.”

“That just means he trusts you. Honestly dude, I would trust you with my soul, too, but I’m not gonna soul-bond with you, ya know?”

Swap groaned and dropped his head hard on the bar counter, hitting it a few times before Sans grabbed the back of his hoodie.

“Dude! Calm down, you’re coming off like a basket case,” Sans scolded.

Swap kept his head on the bar but stopped hitting it and took a deep breath.

“I just never thought anyone would ever want to be with me,” Swap said. “I’m just so used to doing everything by myself. I want that sort of companionship but it’s still scary. Strength means so much to Fell, bonding with me might make him weak.”

“You’re strong too, though, you know that, don’t you, bud?” Sans said, rubbing his back. “Our HP sucks, sure, but I wouldn’t want to go up against you or me in a fight.”

“I guess,” Swap sat up. “Do you think the Karmic Retribution thing would affect him?”

“Maybe the way his attacks cause damage, but nothing should change him personally. Not like we use attacking magic much these days.”

“And what if we have another incident, like what we had a few weeks ago?”

“Then I guess we’ll find out,” Sans took a chug from the ketchup bottle. “I do think the pros outweigh the cons in all of this, and while your concerns for Fell are valid, as long as he - the both of you - understand any and all consequences, and if you two dorks love each other, I don’t see any reason to not go through with it.”

Sans leaned back on the barstool, his posture indicating he said everything he wanted to say. Swap took another swig of honey, knowing that he still had a lot to think about.

* ~ * ~ * ~ * ~ * ~ * ~ * ~ * ~ * ~ *

“He hates me now, that must be it!” Fell fretted as he paced. “It was stupid of me to every suggest such a thing! Stupid of me to ever think he would want someone like me! I know I am very cool and quite an admirable role model, but sometimes that is just too much for a monster to take!”

“Edgy-me, you are being positively ridiculous!” Papyrus said as he sighed and shook his head. “Swap cares very much for you! NYEEEH!” Papyrus pounded the tomatoes that he had sitting in the counter and scraped the mess into a pot before turning to Fell to chirp happily, “I know this for a fact because he has told me so!”

“But that was because it was just sex before!”

“Yes, well, things apparently have changed, as you can certainly have sex without caring for someone,” Papyrus said, looking a little uncomfortable to talk about such private matters. “I commend you for making such a move and for wanting such a commitment, just know that it may take Swap some time to come to a decision. I do not think he will want to terminate your relationship and it bears repeating that I know that he cares very much about you.”

Papyrus cried out as he punched an onion and a few garlic cloves together with some basil leaves, adding them to the tomatoes.

While he did that, Fell sank into silence as his mind went over the entire situation - Papyrus was the easiest one to talk to, he knew he could get a straightforward answer without any sort of beating about the metaphorical bush. He was hesitant to talk to Blue because he worried about saying something that could be taken out of context, then Swap hearing it and getting the wrong ideas or impressions - that already happened a few times when they all had first met. Sans would say anything to get the edgy skeleton to leave him alone, and this sort of thing was too embarrassing to bring up to his brother, and Red had admitted to being one of the worst people to ask about relationship advice of any kind.

“Hello Papyrus!” Blue said cheerily as he slipped into the kitchen. “Ah, Fell! I was hoping that I would find you here, since I could not find you at home!”

“Oh, Blue! I did not hear you knocking!” Papyrus said, wiping his hands clean and rushing over to grab his friend into a huge hug.

“I didn’t bother, I figured you wouldn’t mind!” Blue said, giggling a little as Papyrus spun him around once before putting him down. “Here, Fell, Papy wanted me to give you this!”

Blue held out a small white envelope. Fell looked at it with worry clear in his face.

“It’s a good thing,” Blue said with a wink. “We had a talk.”

Fell’s face dropped from worry to apprehensive, Blue leaned against Papyrus as if he was a wall and grinned. Papyrus gave Fell a meaningful smile and nod, Fell made a small nod in return and opened the envelope with slightly shaking hands.

Inside was a small card, orange in the outside, messy handwriting on the inside:

_Hey babe, I will meet you in your room tonight at eight o’clock. I love you._

There was no signature - not that it was needed.

Papyrus and Blue were both beaming as Fell looked up, his face still mostly neutral, but his soul was doing victorious flip-flops and his eyes had a hint of a hopeful sparkle.

* ~ * ~ * ~ * ~ * ~ * ~ * ~ * ~ * ~ *

“Smells great, Boss,” Red said, grinning up at Fell as he set a plate of dinner down in front of him. “Thanks.”

Fell gave his brother a small smile as he sat, watching the other eat and ignoring his own plate.

“You okay, bro?” Red asked, noticing he was being watched.

“Swap is coming over later,” Fell said.

“Yeah? To talk about your proposal?”

“I am assuming so, he sent Blue over to Sans and Papyrus’ with this.”

He slid the note across the table, Red took it up and looked inside.

“I see, well, I think that’s good! I’m sure he’s gonna say yes; who wouldn’t want a cool guy like you as their soul-mate?”

“You do like him, don’t you Sans?”

Red put his fork down and chuckled as he leaned back in his chair, folding his hands behind his head.

“Ah, Pap, still lookin’ get big bro’s approval? I’m flattered.”

“Don’t be a dick about this.”

“Ha ha ha! Sorry, sorry, it’s rare that I see you have any sort of hesitation about anything or ask me for any sort of help or approval,” Red sighed, leaning forward on the table. “You took care of a lot of stuff.”

“You did too, Sans, and you did it as a child. I couldn’t do much yet, and you wouldn’t let me; it was only when I became strong enough to overpower you did you finally relent.”

“Yeah, very true,” Red sighed. “So, do you want me to stay in my room in case you need me or do you want the house to yourself?”

“If I may have the house to myself, please?”

“No prob, was lookin’ to hang out at Grillz’s place,” Red took one more bite of his dinner, wiping his mouth with the back of his sleeve before standing up and going over to his brother, giving his shoulder a light punch. “You got protection, bro?”

“Why would I need prote-!” Fell started, but then he growled. “Oh my God, Sans, get out!”

Red left the house a little while later, still giggling.

* ~ * ~ * ~ * ~ * ~ * ~ * ~ * ~ * ~ *

Fell was pacing in his room, and he only stopped when he heard the front door open. He had texted Swap earlier to let him know the door was unlocked, and he recognized the soft footsteps coming up the stairs. He had stopped in the middle of his room, his eyes on the door. A gentle knock came before the turn of the knob, and Swap poked his head inside, smiling at Fell before going all the way in and shutting the door behind him.

“My brother has gone to Grillby’s for the evening,” Fell said when Swap went to lock the door.

“Okay. Hey babe,” Swap said.

“Hello, love,” Fell said, smiling.

“Nyeh, heh, d’you know you are really bad at hiding your nervousness?” Swap said with a chuckle.

“What?! I am not!”

“Yes, you are; your smile is a little forced and you only tap your fingers when you’re nervous.”

Swap moved closer and reached up for Fell’s hands. Fell uncrossed his arms and placed them in Swap’s waiting palms. He lifted Fell’s hands up to his mouth so he could kiss them.

“I’m sorry for making you wait,” Swap said, taking a step back and letting Fell’s hands slip out of his.

“I told you that you could take your time, and I meant it,” Fell said, relaxing a little now so that his smile was more genuine.

“Still,” Swap sighed, putting his hands over his sternum and closing his eyes.

Fell opened his mouth to speak, but a bright flash of pale orange light filled the room for a moment, and it faded into a small heart that Swap was cradling in his hands.

“I, I know I said that I don’t really believe in the soulmate stuff, but I do love you, so much it makes me ache, and I think this is the best way for us to protect each other, and it will make you happy.”

“It’s not worth it if it’s going to make you miserable,” Fell said.

“It won’t,” Swap moved forward so that they were only inches apart. “I really mean it, Fell, I trust you, and I love you.”

He tipped his hands towards Fell, who brought up his hands to accept Swap’s soul.

It felt heavier than Fell expected – a sign of a monster burdened with incredible stress - Swap blushed and looked away as Fell took a moment to inspect it. He was a little concerned that it was so pale, Swap’s magic tended to be a pale orange to begin with, but this was a translucent tone. The surface was mostly smooth, but there was a scar that ran diagonally across it that made him feel a little uneasy.

Fell looked back up at Swap, who was beginning to shift his weight from one foot to the other nervously.

“Don’t worry, my love, I’ll take care of you,” Fell said softly with a smile.

“Nyeh, m-maybe this isn’t such a good ide-ahhhhh!”

Fell smirked; Swap had a bit of a thing where his nerves tended to fail him and he would start stuttering to get out of whatever it was he was chickening out of, but Fell responded to this with a slow lick across Swap’s soul.

Swap moaned and shivered, he went weak in the knees, and he had gripped onto Fell to keep his balance. Fell, being the stronger of the two, had no problem being a base for Swap as he repeated the action. Swap gripped his shoulders tight, panting and letting out soft moans, he knew the feeling would be intense, but this was almost too much.

“A little too much for you, darling?” Fell purred, lifting his other hand to brush across Swap’s cheekbone. “Poor dear, come with me.”

Swap didn’t feel like he had much of a choice as Fell circled an arm around his back and lead him over to the bed, gently pushing him down on it as he kissed him. How he also held onto his soul, he didn’t really know, he just figured his lover was just that cool of a guy.

Fell straddled his hips and leaned over for another kiss, his thumb caressing the surface of Swap’s soul. He swallowed Swap’s cries, deepening the kiss, grinding his hips into him. Swap was soon moving under him, his hands had been alternating between flailing and gripping the mattress, but now began to grip onto Fell, pulling him in closer.

“Mmm, good boy, relax now,” Fell murmured as he pulled away to sit up.

Swap whined but stayed put instead of following. His eye-lights had turned hazy, but they were still focused on Fell.

Fell brought Swap’s soul to his mouth again and gently kissed it, trailing the very tip of his tongue lightly along the pale scar. Swap gripped onto the sheets again as he tried to hold back a moan, and Fell responded by pressing his tongue harder against it.

Swap bucked and cried out, but Fell was unmoving.

“I did that to prove a point,” Fell murmured. “This is not the time to hide or pretend, to be coy or shy. As you told me the night I gave you my soul, let it go, I got you.”

Fell continued to bathe the soul with his tongue, kissing, and even nibbling along its edges. Swap writhed beneath him, his moans growing louder, but when he brought a hand up to instinctually cover his mouth, Fell smirked and pinned it down.

“Ah, ah, ah,” he chuckled. “Cum for me, Papyrus.”

Fell pressed Swap’s soul to his mouth, his teeth gently scraping the surface, sucking up the excess magic that was pouring out.

“Nnggh, a-a-ahhhhh!” Swap cried out.

“Good, good boy,” Fell said breathlessly. “H-hold on for me, now.”

Swap trembled as he watched Fell bring out his own soul. It didn’t look too much different than from the first time, though it seemed brighter, and Swap could feel its energy, and his soul was crying out for it. But…

“W-wait,” Swap stammered, gripping onto the wrist that held Fell’s soul. “A-are y-you sure? Wh-wh-what if it mum-makes you w-we-weak?”

Fell smiled and leaned down.

“I will always be strong as long as I am with you.”

Swap whined into the kiss that followed, relaxing a little as Fell pulled away.

“Would you still be my soul-bound mate?” Fell asked.

“Yes, I will,” Swap murmured.

“Good.”

Fell allowed the souls to float on his palms, the two skeletons watching as they spun in place. It was beginning to make them both dizzy when suddenly, both souls rose from Fell’s hands, sped towards one another, and meshed above them.

The feeling was intense and incredible, the two only able to gasp and grip onto each other as their souls began to mate. Their magic began humming through their bodies, hot and tingling.

“Fell, please, do something,” Swap begged.

Fell dropped forward to grip Swap’s face and kiss him deeply. It was a strange feeling this time, it felt closer, more intimate, more special. Fell began rubbing his body against Swap, his magic forming and pressing into the other through their clothes, and it coaxed Swap’s magic to form in kind. Fell then reached down for Swap’s hands, twining their fingers together and pressing them above Swap’s head, feeling the rush that went through Swap - he did have a thing for being restrained.

“Please, Fell, please,” Swap begged.

Fell gave a small grunt, indicating he knew what the other wanted, feeling it more as their souls bonded.

Swap whined in protest as Fell pulled away, and though Fell felt it as well, it was necessary for them to move on to the next step.

“Shh, my love, I’ll take care of you,” Fell said.

Swap’s hands joined his in getting them both undressed, their clothes littering the floor in a matter of seconds. Both of their magics were glowing bright as the two lovers stared at each other hungrily. Swap lunged forward for Fell as the other pulled him in for another kiss, helping Swap to situate himself in his lap.

Words were no longer necessary as they were past the need for hesitation and questions. Permission was given through their eyes and soon they were joined in body as well as soul.

It was an odd feeling; their souls binding together gave them the ability to feel what the other felt, so as Fell’s thick cock pressed inside of Swap, the edgy skeleton felt as if he was also being penetrated as Swap felt like he was surrounded by a glorious tightness and heat. They both moved slowly, savoring the moment, enjoying what the other had to offer. Mouths met, the air was thick with moans and panting, hot breath ghosting over bones that glistening with their magic. Their pace began to pick up, both desperate to reach that peak.

“Fuck, fuck, Fell, please!” Swap begged, gripped onto him tightly.

“Stars, yes, cum for me, my love,” Fell said, pressing forward to pin Swap against the mattress, driving into him harder and faster.

Above them, their souls glowed brightly, Swap crying out as he came, with Fell following a moment later, driving in as deep as he could go and staying there, Swap wrapping his legs around his waist and holding him close.

“I love you, love you so much,” Swap whispered.

“I love you, too,” Fell murmured, moving to kiss him again.

They came down from their high slowly, as their souls also returned to their rightful places. Each were a slightly different hue, taking a bit of the color from their mate on. Swap felt a little bolster in his constitution, the result of sharing Fell’s strength, and a sense of serenity that he never remembered having before came over Fell, the influence from his mate’s soul.

“This is going to be a little weird, huh?” Swap murmured.

“Yes, it is something new, but I am very much looking forward to going down this new road with you,” Fell said.

“Heh, you cheesy asshole.”

“Lazy prick.”

They nuzzled each other’s faces, and spent the rest of the night in each other’s arms, connected, and content, drifting in and out of sleep, making love once or twice more. The missing holes each had felt in their souls before now filled, both Papyrus’ feeling a sense of relief that neither of them would ever be alone again.


End file.
